Get ready for a novella-length post:
I'm a little fuzzy on the specific difference between versions. I just have full, 'regular' Cubase 4. (IE, the Cubase with no subtitle or extra letters..) but to be honest I have hardly touched it since I finally got the hang of Ableton Live. Both are amazing programs, though. I still use Cubase for my mastering. It seems to have the most 'transparent' audio engine -- as in, what you put in is what you'll get out of it. Other programs, say Reason for instance, seem to 'color' the final exported .wav file in a very subtle way..
Anyway, there are a lot of different things that are just going to take time to learn. There is no 'right' way to produce electronic (or any) music of any flavor, though there are some techniques that are considered 'standard' or 'popular'.
First, I strongly suggest you find some production forums. The SS.org community is amazing, and this is my favorite forum hands down, but there seem to only be a hand full of us who A) listen to and/or appreciate electronic music generally speaking and B) also produce electronic music ourselves. Try to find a forum where the
focus is on what you're trying to learn.
If you have little-to-no experience, you're going to need some time to just learn the software's interface, and the bare-bone basics of production. Once you get that stuff out of the way, you can start worrying about more intense stuff like programming your own synth presets, drum kits, what 'sidechain compression' or 'ducking' is, and so on.
Just have as much fun as you can. If you start to get frustrated, take a break, come back later.
To answer your more specific questions:
You should already have enough to get started. What's nice about programs like cubase is that they allow you to sequence midi and raw audio files, so in the beginning you can just use audio files of drum breaks you like and focus on learning the synth stuff you'll use for the melodic or FX elements of your tunes. There are *plenty* of free VST samplers and synths out there for you to fill in any blanks that didn't come with the program (I don't know if your version includes any drum machines or synths, etc), but bear in mind you usually get what you pay for. Once you get your feet under you though, you'll probably want to invest in some version of nice VST synth, like Rob Papen's Albino, or whatever.
You can program everything via mouse and keyboard, and honestly I would recommend that to start, or at least -- that's how I started. Again, once you get your feet under you, a MIDI keyboard will really speed up the game and become an invaluable resource, but it's pretty useless until you have the foundation of programming knowledge under your belt.
The need for VST plugins depends on what your needs are. Basically, they're what you said -- extra effects, synths, drum programs, etc. If your software doesn't have some tool that you need, try to find a plugin for it.
Here are some final tips I've got for you:
1. Find books on producing, mastering, etc. Read them. Seriously. The Cubase manual has TONS of golden tips in it. 'The Mixing Engineer's Handbook' was great, and enjoyable.
2. Less is more. It's quick and easy to get carried away with 32 tracks of different harmonies and sounds, but the simpler your arrangement is, the more powerful it has the potential to sound after you mix it all down. You'll eventually learn all about frequencies, and how a 'busy' track can be pushing too many elements in the same frequency range, making things sound really harsh.
3. Do NOT, under any circumstances, allow your self to get into the mind-set of "I'll be able to start writing amazing tunes as soon as I get (random hardware or software item)". Work with what you have. You'd be surprised how little you can do a lot with.
4. Learn the difference between the different types of waves: Sine, Saw, Triangle, Square, etc (
http://upload.wikimedia.org/wikipedi.../Waveforms.svg). These are the fundamental building blocks of ALL synth sounds, and an understanding of what each sounds like (unaltered in all it's raw glory) is perhaps the most important tool you'll ever have when programming your own synth sounds from scratch.
5. I can't stress this enough: have fun. If you don't enjoy it, there's no point in doing it. The days of the 'insta-rich dj/producer superstar' are officially behind us, at least for now. There's no money in electronic music production, unless you're Paul Oakensuck or Tiestblow, and are writing the soundtrack for the next multi-million-dollar video game or movie.
6. Toss me a PM when you're stuck on something, and I'll be glad to offer any insight I might have.
Hope this is helpful! Good luck to you!